This invention is directed generally to a touch panel assembly used with an interactive cathode ray tube (CRT) display system for changing the graphics in response to a user touching one or more selected areas of the CRT faceplate and particularly to means for supporting a touch panel assembly in fixed relationship to a CRT.
Conventional graphics display apparatus include a CRT and a plurality of light or other energy sources and receptors generating a network or grid of crossing energy paths closely adjacent to the front of the CRT faceplate. Interruption of an energy path, for example by a user touching the faceplate, results in a signal to the CRT graphics controller for changing the graphics displayed in accordance with the area touched and the system computer program. The touch panel, as used herein includes the structure supporting the energy sources and receptors.
There are many touch panel arrangements extant. A particularly useful one is disclosed in copending application Ser. No. 408,096 filed Aug. 13, 1982 in the names of Rowe and Fitzgibbon, which application has been abandoned in favor of continuation application Ser. No. 619,098, filed June 11, 1984, assigned to the present assignee, in which a plurality of light sources is positioned along each axis with a single light collection device or plate, constructed of light transmissive material such as plastic disposed along the respective opposite axis. The two plates are arranged with their forward ends disposed to the sides of the CRT faceplate to enable collection of light from the opposite arrays of light sources and for direction of that light rearwardly to a light collection area. Thus, rather than having individual light pipes or receptors, a single horizontal and a single vertical light collector plate is used.
The light sources are conveniently arranged on a printed circuit board and supported adjacent to the CRT faceplate opposite the light collecting plates or receptors. The collection plates are fairly massive and must be rigidly supported with respect to their respective sources. Depending upon the wavelengths of the energy sources used, the permissible misalignment between the sources and the receptors may be extremely small. Consequently, the touch panel assembly should maintain the sources and receptors in alignment with each other and should preferably hold them in fixed relationship to the CRT faceplate.